The present invention relates generally to web winding apparatus, and more particularly, is directed to web winding apparatus for alternately winding a web onto cores mounted on two mandrels at fixed positions.
In many instances, a silicone layer has a paper or plastic top layer adhesively mounted thereon. The top layer is printed with labels, and the top layer is die cut around the labels. Then, the silicone layer with labels thereon is wound on a core. During a labeling operation, the labels are removed and applied, for example, to containers. The remaining top layer therefore has a plurality of openings therein, and is called a skeleton or matrix, the latter term being used herein.
The matrix is wound onto a disposal or rewind core mounted on a mandrel. When the rewind roll (core plus matrix) acquires a predetermined diameter of matrix thereon, it must be removed, and a new rewind core mounted on the mandrel. However, this requires shutting down the machine, resulting in downtime. This becomes cumbersome in practice, and costly.
In U.S. Pat. No. 5,810,280 to Ryan et al and having a common assignee herewith, there is disclosed a matrix rewinder, in which a matrix or skeleton of a used web is wound onto a core on a mandrel for removal. In order to provide that the machine is not stopped, three mandrels are provided offset from each other by 120.degree., and are sequentially brought into position for rewinding the matrix. However, the device of this patent does not always work properly with some types of webs, since the webs do not break, but must be cut.